The pharmaceutical industry requires considerable quantities of water of high purity such as USP purified water and USP water for injection. The standards for each are well known but in general, USP purified water must be obtained from water which meets Environmental Protection Agency “drinking water” standards or comparable standards of the European Union or Japan. It must not contain any added substances and must be obtained by a suitable process and meet certain requirements relating to electrical conductivity as the electrical conductivity of water increases with the increasing presence of ions of various sorts, indicating impurities.
USP water for injection must meet all of the requirements of USP purified water. Further, it must be obtained by distillation or reverse osmosis and meet the requirements of the Bacterial Endotoxin test and contain no more than 0.25 Endotoxin units per milliliter. It must be prepared by a suitable method and apparatus so as to minimize microbial growth.
Systems utilized heretofore to produce such water are relatively complex, have a high microbial load and a relatively low purified water recovery rate. Many are approved only for USP purified water production and not approved for the production of water for injection. Depending upon the system, organic and microbial bioburden may be present throughout until the water to be purified is subject to heating in a distilling step. This can result in a high organic load and bioburden on the distillation apparatus. Where it is desired to reduce the bioburden on the distilling apparatus one may use a reverse osmosis purification step prior to the distilling step. While this may produce some improvement, the reverse osmosis membrane is subject to biofouling.
The systems also typically employ cartridge filters, multimedia filters and/or carbon filters. Multimedia filters typically remove suspended matter down to only about 20-30 microns and carbon filters having a high bio-growth rate and require regular sanitization which increases system maintenance costs.
Consequently, there is a real need for a simplified water purification capable of providing purified water to USP purified water or USP water for injection standards, and specifically a system that is relatively simple in construction and operation and which avoids high organic load and bioburden when distilling and which minimizes the potential for high biogrowth rates at various points in the system.